Fusible plug.



WILLIAM DREW, OF PHILADELPHIA, PENNSYLIANIA.

FUSIBLE PLUG.

Specification of Letters` Patent.

Patented apr. 11, 1916,

Application filed september 15, 1914. serieu No, 861,768.`

To all whom t may concern:

Be it known that I, WILLIAM DREW, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Fusible Plugs, of which the following is a specification.

My invention relates to improvements in fusible plugs, the object of the invention being to provide a fusible plug which can be readily removed and replaced without disturbing the casing of the plug and which plug extends entirely through theV casing and follower, lling the same from the fire to the water side of the plug, so that there is no space to hold water.

A further object is to provide a fusible plug widest at its center and tapering to both ends, so that both ends are oftruncated conical form, one conical end fitting the conical bore of the casing, and the other conical end fitting the conical bore of the follower, so that when the latter is screwed into place, the plug is securely held and made absolutely water tight.

Y VWith these'and other objects in view, the

invention consists in certain novel featuresl of construction, and combinations and arrangements of parts as will be more fully hereinafter described and pointed out in the claim.

In the accompanying drawings: Figure 1 is a view in longitudinal section illustrating my improvements. Fig. 2 is an end view,

and Fig. 8 is a perspective view of thev fusible plug. A

1 represents an externally screw-threaded.

casing which is screwed into an opening 2A in the boiler sheet 3 directly above the re boX. The casing 1 is provided in its end with an internally screw-threaded recess 4 to receive a screw-threaded follower 5, and said casing 1 is provided with an angular enlargement 6, while the follower 5 is provided with an angular enlargement 7 to receive an ordinary wrench to facilitate the movements of the parts.

Casing 1 is provided with a tapering or conical bore 8 extending from the inner end of the recess 4lwhere said bore is of greatest diameter to the end of the casing where the bore is of least diameter.

The follower 5 is provided with an internal truncated conical bore 9, largest in diameter at the inner end of thev follower,

andl gradually `decreasing in diameter to the outer end of the follower.

1 0 represents my improved fusible plug which is preferably of Banca tin, and which 1s of greatest diameter midway its ends, and tapers from the center to both ends. The plug l0 at one end, ts the bore 8 of casing 1, and at its other'end fits the bore 9 of follower 5, so that when said follower is screwed tightly into place, practically the` entire surface of the plug will be frictionally engaged, one-half of the plug engaged by the casing, and the other half by the follower. n

Iheplug is of a length to extend from the end of theA casing to the end of the follower, and lies flush with the metal surfaces of the casing and follower. When it 1s desired to remove the plug, it is simply necessary to remove the follower when the plug can be readilydisplaced from they casing and replaced by a new plug. Y

When the water falls below the proper level, the heat of the ire will rapidly fuse the plug, and as the plugV is tapering in form from the center to both ends, it will lflow freelyand entirely out of the casing and follower, and there will be a full'and unobstructed passage for the water or steam.

My improved construction of plug is absolutely steam and water tight, and yet can be readily removed and replaced as may be desired.

Various slight changes might be made in the general form and arrangement of parts described without departing from my invenl tion, and hence I do. not limit myself to the precise details set forth, but consider myself atliberty to make such changes and alterations as fairly fall. within the spirit and scope of the appended claim.

Having Ythus described my invention,

what I claim as new` and desire to secure by Letters Patent is: c

The combination with an externally screw-threaded casing having an internal screw-threaded recess in one end, and a conical tapering bore largest in diameter at the inner end of said recess and decreasing in diameter to the end ofthe casing, of an externallyscrew-threaded follower adapted to Vscrew into the recess in the casing and having a truncated conical tapering bore largest in diameter at the inner end of the follower, and decreasing in diameterto the outer end of the follower, and a plug of fusible maferial largest in diameter at its center and In testimony whereof l have signed my tapering to both ends, the largest diameter neme to this specification in the presence of 10 of the plug located between the inner end two subscribing witnesses.

of the follower and the inner end of the recess, seid plug fitting the bores of the cas VLLAM DREN. ing and the follower and extending from the 1Witnesses:

extreme end ofthe follower to the extreme IVI. E. DITLUs,

end of the casing, substantially as described. CHAs. E. Po'rTs.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

